This invention relates generally to the structure of soles of shoes and other footwear, including soles of street shoes, hiking boots, sandals, slippers, and moccasins. More specifically, this invention relates to the structure of athletic shoe soles, including such examples as basketball and running shoes.
More particularly, in it simplest conceptual form, this invention is the structure of a conventional shoe sole that has been modified by having its sides bent up so that their inner surface conforms to a shape nearly identical but slightly smaller than the shape of the outer surface of the sides of the foot sole of the wearer (instead of the shoe sole sides conforming to the ground by paralleling it, as is conventional). The shoe sole sides are sufficiently flexible to bend out easily when the shoes are put on the wearer's feet and therefore the shoe soles gently hold the sides of the wearer's foot sole when on, providing the equivalent of custom fit in a mass-produced shoe sole.
Still more particularly, this invention relates to variations in the structure of such soles using a theoretically ideal stability plane as a basic concept, especially including structures exceeding that plane.
The parent '598 application clarified and expanded the applicant's earlier filed U.S. application Ser. No. 07/680,134, filed Apr. 3, 1991.
The applicant has introduced into the art the concept of a theoretically ideal stability plane as a structural basis for shoe sole designs. The theoretically ideal stability plane was defined by the applicant in previous copending applications as the plane of the surface of the bottom of the shoe sole, wherein the shoe sole conforms to the natural shape of the wearer's foot sole, particularly its sides, and has a constant thickness in frontal or transverse plane cross sections. Therefore, by definition, the theoretically ideal stability plane is the surface plane of the bottom of the shoe sole that parallels the surface of the wearer's foot sole in transverse or frontal plane cross sections.
The theoretically ideal stability plane concept as implemented into shoes such as street shoes and athletic shoes is presented in U.S. Pat. No. 4,989,349, issued Feb. 5, 1991 and U.S. Pat. No. 5,317,819, issued Jun. 7, 1994, both of which are incorporated by reference; and pending U.S. application Ser. No. 07/400,714, filed Aug. 30, 1989; U.S. Ser. No. 07/416,478, filed Oct. 3, 1989; U.S. Ser. No. 07/424,509, filed Oct. 20, 1989; U.S. Ser. No. 07/463,302, filed Jan. 10, 1990; U.S. Ser. No. 07/469,313, filed Jan. 24, 1990; U.S. Ser. No. 07/478,579, filed Feb. 8, 1990; U.S. Ser. No. 07/539,870, filed Jun. 18, 1990; and U.S. Ser. No. 07/608,748, filed Nov. 5, 1990.
PCT applications based on the above patents and applications have been published as WO 90/00358 of Jan. 25, 1990 (part of the '349 Patent, all of the '819 Patent and part of '714 application); WO 91/03180 of Mar. 21, 1991 (the remainder of the '714 application); WO 91/04683 of Apr. 18, 1991 (the '478 application); WO 91/05491 of May 02, 1991 (the '509 application); WO 91/10377 of Jul. 25, 1991 (the '302 application); WO 91/11124 of Aug. 08, 1991 (the '313 application); WO 91/11924 of Aug. 22, 1991 (the '579 application); WO 91/19429 of Dec. 26, 1991 (the '870 application); WO 92/07483 of May 14, 1992 (the '748 application); WO 92/18024 of Oct. 29, 1992 (the '598 application); and WO 94/03080 of Feb. 17, 1994 (the '523 application). All of above publications are incorporated by reference in this application to support claimed prior inventions that are incorporated in combinations with other elements disclosed in the incorporated applications.
This new invention is a modification of the inventions disclosed and claimed in the earlier applications and develops the application of the concept of the theoretically ideal stability plane to other shoe structures. Each of the applicant's applications is built directly on its predecessors and therefore all possible combinations of inventions or their component elements with other inventions or elements in prior and subsequent applications have always been specifically intended by the applicant. Generally, however, the applicant's applications are generic at such a fundamental level that it is not possible as a practical matter to describe every embodiment combination that offers substantial improvement over the existing art, as the length of this description of only some combinations will testify.
Accordingly, it is a general object of this invention to elaborate upon the application of the principle of the theoretically ideal stability plane to other shoe structures.
The purpose of this application is to specifically describe some of the most important combinations, especially those that constitute optimal ones, that exist between the applicant's U.S. patent application Ser. No. 07/400,714, filed Aug. 30, 1989, and subsequent patents filed by the applicant, particularly U.S. Ser. No. 07/416,478, filed Oct. 3, 1989, as well as to provide an explicit basis for describing elements from those two applications in combination with any other useful combinations possible from elements disclosed in any of the other incorporated patents, applications, or PCT publications listed above.
The '714 application indicated that existing running shoes are unnecessarily unsafe. They profoundly disrupt natural human biomechanics. The resulting unnatural foot and ankle motion leads to what are abnormally high levels of running injuries.
Proof of the unnatural effect of shoes has come quite unexpectedly from the discovery that, at the extreme end of its normal range of motion, the unshod bare foot is naturally stable, almost unsprainable, while the foot equipped with any shoe, athletic or otherwise, is artificially unstable and abnormally prone to ankle sprains. Consequently, ordinary ankle sprains must be viewed as largely an unnatural phenomena, even though fairly common. Compelling evidence demonstrates that the stability of bare feet is entirely different from the stability of shoe-equipped feet.
The underlying cause of the universal instability of shoes is a critical but correctable design flaw. That hidden flaw, so deeply ingrained in existing shoe designs, is so extraordinarily fundamental that it has remained unnoticed until now. The flaw is revealed by a novel new biomechanical test, one that is unprecedented in its simplicity. It is easy enough to be duplicated and verified by anyone; it only takes a few minutes and requires no scientific equipment or expertise. The simplicity of the test belies its surprisingly convincing results. It demonstrates an obvious difference in stability between a bare foot and a running shoe, a difference so unexpectedly huge that it makes an apparently subjective test clearly objective instead. The test proves beyond doubt that all existing shoes are unsafely unstable.
The broader implications of this uniquely unambiguous discovery are potentially far-reaching. The same fundamental flaw in existing shoes that is glaringly exposed by the new test also appears to be the major cause of chronic overuse injuries, which are unusually common in running, as well as other sport injuries. It causes the chronic injuries in the same way it causes ankle sprains; that is, by seriously disrupting natural foot and ankle biomechanics.
It was a general object of the '714 invention to provide a shoe sole which, when under load and tilting to the side, deforms in a manner which closely parallels that of the foot of its wearer, while retaining nearly the same amount of contact of the shoe sole with the around as in its upright state.
It was still another object of the '714 invention to provide a deformable shoe sole having the upper portion or the sides bent inwardly somewhat so that when worn the sides bend out easily to approximate a custom fit.
It was still another object of the '714 invention to provide a shoe having a naturally contoured sole which is abbreviated along its sides to only essential structural stability and propulsion elements, which are combined and integrated into the same discontinuous shoe sole structural elements underneath the foot, which approximate the principal structural elements of a human foot and their natural articulation between elements.
The '478 invention relates to variations in the structure of such shoes having a sole contour which follows a theoretically ideal stability plane as a basic concept, but which deviates therefrom outwardly, to provide greater than natural stability. Still more particularly, this invention relates to the use of structures approximating, but increasing beyond, a theoretically ideal stability plane to provide greater than natural stability for an individual whose natural foot and ankle biomechanical functioning have been degraded by a lifetime use of flawed existing shoes.
The '478 invention is a modification of the inventions disclosed and claimed in the earlier application and develops the application of the concePt of the theoretically ideal stability plane to other shoe structures. As such, it presents certain structural ideas which deviate outwardly from the theoretically ideal stability plane to compensate for faulty foot biomechanics caused by the major flaw in existing shoe designs identified in the earlier patent applications.
The shoe sole designs in the '478 application are based on a recognition that lifetime use of existing shoes, the unnatural design of which is innately and seriously flawed, has produced actual structural chances in the human foot and ankle. Existing shoes thereby have altered natural human biomechanics in many, if not most, individuals to an extent that must be compensated for in an enhanced and therapeutic design. The continual repetition of serious interference by existing shoes appears to have produced individual biomechanical chances that may be permanent, so simply removing the cause is not enough. Treating the residual effect must also be undertaken.
Accordingly, it was a general object of the '478 invention to elaborate upon the application of the principle of the theoretically ideal stability plane to other shoe structures.
It was still another object of the '478 invention to provide a shoe having a sole contour which deviates outwardly in a constructive way from the theoretically ideal stability plane.
It was another object of the '478 invention to provide a sole contour having a shape naturally contoured to the shape of a human foot, but having a shoe sole thickness which is increases somewhat beyond the thickness specified by the theoretically ideal stability plane.
It is another object of this invention to provide a naturally contoured shoe sole having a thickness somewhat greater than mandated by the concept of a theoretically ideal stability plane, either through most of the contour of the sole, or at preselected portions of the sole.
It is yet another object of this invention to provide a naturally contoured shoe sole having a thickness which approximates a theoretically ideal stability plane, but which varies toward either a greater thickness throughout the sole or at spaced Portions thereof, or toward a similar but lesser thickness.
The '302 invention relates to a shoe having an anthropomorphic sole that copies the underlying support, stability and cushioning structures of the human foot. Natural stability is Provided by attaching a completely flexible but relatively inelastic shoe sole upper directly to the bottom sole, enveloping the sides of the midsole, instead of attaching it to the top surface of the shoe sole. Doing so puts the flexible side of the shoe upper under tension in reaction to destabilizing sideways forces on the shoe causing it to tilt. That tension force is balanced and in equilibrium because the bottom sole is firmly anchored by body weight, so the destabilizing sideways motion is neutralized by the tension in the flexible sides of the shoe upper. Still more particularly, this invention relates to support and cushioning which is provided by shoe sole compartments filled with a pressure-transmitting medium like liquid, gas, or gel. Unlike similar existing systems, direct physical contact occurs between the upper surface and the lower surface of the compartments, providing firm, stable support. Cushioning is provided by the transmitting medium progressively causing tension in the flexible and semi-elastic sides of the shoe sole. The compartments providing support and cushioning are similar in structure to the fat pads of the foot, which simultaneously provide both firm support and progressive cushioning.
Existing cushioning systems cannot provide both firm support and progressive cushioning without also obstructing the natural pronation and supination motion of the foot, because the overall conception on which they are based is inherently flawed. The two most commercially successful proprietary systems are Nike Air, based on U.S. Pat. No. 4,219,945 issued Sep. 2, 1980, U.S. Pat. No. 4,183,156 issued Sep. 15, 1980, U.S. Pat. No. 4,271,606 issued Jun. 9, 1981, and U.S. Pat. No. 4,340,626 issued Jul. 20, 1982; and Asics Gel, based on U.S. Pat. No. 4,768,295 issued Sep. 6, 1988. Both of these cushioning systems and all of the other less popular ones have two essential flaws.
First, all such systems suspend the upper surface of the shoe sole directly under the important structural elements of the foot, particularly the critical the heel bone, known as the calcaneus, in order to cushion it. That is, to provide good cushioning and energy return, all such systems support the foot's bone structures in buoyant manner, as if floating on a water bed or bouncing on a trampoline. None provide firm, direct structural support to those foot support structures; the shoe sole surface above the cushioning system never comes in contact with the lower shoe sole surface under routine loads, like normal weight-bearing. In existing cushioning systems, firm structural support directly under the calcaneus and progressive cushioning are mutually incompatible. In marked contrast, it is obvious with the simplest tests that the barefoot is provided by very firm direct structural support by the fat pads underneath the bones contacting the sole, while at the same time it is effectively cushioned, though this Property is underdeveloped in habitually shoe shod feet.
Second, because such existing proprietary cushioning systems do not provide adequate control of foot motion or stability, they are generally augmented with rigid structures on the sides of the shoe uppers and the shoe soles, like heel counters and motion control devices, in order to provide control and stability. Unfortunately, these rigid structures seriously obstruct natural pronation and supination motion and actually increase lateral instability, as noted in the applicant's pending U.S. applications Ser. No. 07/219,387, filed on Jul. 15, 1988; U.S. Ser. No. 07/239,667, filed on Sep. 2, 1988; U.S. Ser. No. 07/400,714, filed on Aug. 30, 1989; U.S. Ser. No. 07/416,478, filed on Oct. 3, 1989; and U.S. Ser. No. 07/424,509, filed on Oct. 20, 1989, as well as in PCT application No. PCT/US89/03076 filed on Jul. 14, 1989. The purpose of the inventions disclosed in these applications was primarily to provide a neutral design that allows for natural foot and ankle biomechanics as close as possible to that between the foot and the ground, and to avoid the serious interference with natural foot and ankle biomechanics inherent in existing shoes.
In marked contrast to the rigid-sided proprietary designs discussed above, the barefoot provides stability at it sides by putting those sides, which are flexible and relatively inelastic, under extreme tension caused by the pressure of the compressed fat pads; they thereby become temporarily rigid when outside forces make that rigidity appropriate, producing none of the destabilizing lever arm torque problems of the permanently rigid sides of existing designs.
The applicant's '302 invention simply attempts, as closely as possible, to replicate the naturally effective structures of the foot that provide stability, support, and cushioning.
Accordingly, it was a general object of the '302 invention to elaborate upon the application of the principle of the natural basis for the support, stability and cushioning of the barefoot to shoe structures.
It was still another object of the '302 invention to provide a shoe having a sole with natural stability provided by attaching a completely flexible but relatively inelastic shoe sole upper directly to the bottom sole, enveloping the sides of the midsole, to put the side of the shoe upper under tension in reaction to destabilizing sideways forces on a tilting shoe.
It was still another object of the '302 invention to have that tension force is balanced and in equilibrium because the bottom sole is firmly anchored by body weight, so the destabilizing sideways motion is neutralized by the tension in the sides of the shoe upper.
It was another object of the '302 invention to create a shoe sole with support and cushioning which is provided by shoe sole compartments, filled with a pressure-transmitting medium like liquid, gas, or gel, that are similar in structure to the fat pads of the foot, which simultaneously provide both firm support and progressive cushioning.
These and other objects of the invention will become apparent from a detailed description of the invention which follows taken with the accompanying drawings.